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I have a Scania K112TR (Chassis No YS4KC4X2B01809202) and am having problems with overheating. Just been away in the bus over Christmas and had to drive at night to keep the temps down. As soon as any significant load is put on the engine (over 90 km/h it overheats). Even at night it was still at the top end of the temp range (97-98 degrees) I have tested the temp near the sender with a laser thermometer and confirmed that the gauge and light is reading correct. So far I have done the following with no improvement:

Removed radiator and had the top tank taken off, cleaned out and flow and pressure tested (was 25 % blocked)Removed the water pump (twice) and checked that it is OK and the impeller was not turning on the shaft.Replaced the thermostat,(79 degrees)replaced the temp senderReplaced the radiator cap (old one 7 psi - new on 10 Psi)Removed the thermostat ( no change)Changed from 15-40 oil to 20 -50 oilLocked the viscous fan with a metal link between inner and outer. ( no change)System was pressure tested during trip and it was holding pressure.It doesn't appear to be using any coolant.Oil is fine (no water in it)Belts are tight

The engine runs fine and has no knocks of rattles although the oil pressure is not fantastic when it is at operating temperature. Does anyone have any advice or something I may have missed. It is driving me crazy Any help would be appreciated,

Has the radiator got a shroud. Will overheat if the shroud is missing or a poor fit. Any gaps and I mean any spaces between where is picks up air and the radiator core itself will allow air to bypass the radiator. Air is very lazy and will take the easy route rather than flow through the core. Also is there an air ducting directing the air into the radiator core. If you have any sort of gaps plug it with closed cell foam padding, (Clark Rubber) or make up some thin rubber strips to secure and close the gaps. I don't have a Scania and haven't seen one but if they pick air from the side of the bus then getting the gaps plugged is essential as the side is a low pressure area and only gets limited air supply at the best of times. You could make up narrow scoops to help direct the air into the radiator if its a side air pick up but watch the overall width the road authorities are picky on this sort of thing.

Thanks for your input Kelvin12. There is room for improvement in this area and I will fix the small gaps that exist. I had thought about adding an additional scoop on the exterior. The mirror on the side and the side awning already stick out further than the body line so should be no issues with a small scoop. I don't think airflow is the issue as it seems to be a recent development. As it is a motor home I only use it about 3 times a year and the overheating is recent but I have been more aware of it since I replaced the temp gauge as the original jumped around intermittently. The new (2nd hand) one is correct as per the laser thermometer. I have attached some pics of radiator and surrounds.

Is it running an intercooler off the turbo? Just thinking (Always hard when your not looking directly at the vehicle) if it has an intercooler mounted in front of the radiator was that cleaned when the radiator was done? I know you said the motor is running ok but another thing is if there is a boost leak off the turbo side causing the motor to labour more than usual?

No inter-cooler but I checked the core in the oil cooler (was OK) for blockage as the water from the bottom hose flows through it first. I had considered the turbo but don't have the gear at home to test. Will have to wait to go back to work( Army vehicle mechanic (WO2 ASM)) to check the boost. I may do an in-chassis change of the bearings as well

You have a few big holes there especially to the right hand side. Doesn't take much for the air to head down that sort of hole rather than through where you want it to go. The pickup area in the side hatch seems small in area but guess if its been in service then its been OK. Silly question but how is the condition of the core. Has it been flow tested to see what sort of quantity of water is actually flowing through it. Being European it also might need an electric water pump in the system to push the water through quicker.

I reckon you have a blocked block i.e. you only use 3 X 5imes a year, the rest of the time it just sits there with the block slowly corroding and blocking the cooling passages.

This was a problem with our 6V92T and we tried a few different cleaners, all were bloody useless until we tried "Restore " which is a mild acid solution, put it in, ran for a bit and did really, really good flushing afterwards

Since then we have had reason to open up bits and looking inside the block is like a new one, worked for us. When you think about it, you have done everything else, bar the block. Careful of any alloy parts though !

Another thing to look for, many European manufacturers use filters to catch the crap in the cooling system, a blocked one of those would do what you are experiencing.

Your shroud looks to be tight fitting enough to me, if the radiator is performing then it is in the erst of the cooling system

rustbucket,Thanks for the advice. I was hoping it was not the block but in the back of my mind I suspected it might be. I have put a cleaner into the cooling system and it gets to sit in there for about a week or so. I used liquid intelligence engine-cooling-system-cleaning-kit. I was going to put the Cummins product (restore) but they have and "Australia" tax on it and charge double for it compared to the US. I rang and spoke to the Liquid intelligence bloke (Australian product) and was happy that it would suit my needs. It has been i for about 5 days so I am hoping it will work OK. It is a two part cleaner so have another lot to add after the first cleaner has done its job. This product apparently does not eat any of the base metals so seems pretty safe. Fingers crossed....

G'day Marty,looking back several decades we found with RE vehicles that as they aged & everything no longer new & spic that we needed to be more aware of airflow as all of the things that you have looked at don't work as they did when brand new. Looking at your pictures you need to fill in gaps around radiator, put a couple of full length, small height scoops on the intake door, one about a third of the way along from front & about 50 mm high, next at the rear of the mesh about 75mm high. That should increase the flow into the front of the radiator. Also if you have a solid panel rear door on the engine bay it would be worth investigating putting a mesh screen in that door to let the air pressure escape more freely, that would allow the airflow through your radiator to move more freely as the engine bay is already full of hot pressurised air from flow over the diff, gearbox & motor.Good luckTim

hi, cccc, thanks for your reply. finally found problem, the oil in the viscous fan had leaked out and fan not working. now all we need is to keep the oil in. Trying to find some information on replacement parts and correct oil to use. Thanks for your help.

A little off subject here but I am chasing a copy of the K112 and or 113 service manual or workshop manual. A digiatl copy would be great but i would be happy to compile a copy from a hardcopy . Please.let me know if anyone knows where I can get one from. Mal